1. Field
The present disclosure relates to a negative active material, a lithium battery including the negative active material, and a method of preparing the negative active material.
2. Description of the Related Art
Lithium secondary batteries used in portable electronic devices for information and communication, such as personal data assistants (PDAs), mobile phones, and laptop computers, electric bicycles, electric vehicles, and the like have a discharge voltage of about twice that of aqueous batteries, and thus provide a higher energy density.
Lithium secondary batteries include a positive electrode and a negative electrode, each including an active material that allows intercalation and deintercalation of lithium ions, and an organic electrolyte or a polymer electrolyte between the positive and negative electrodes. Lithium batteries produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive and negative electrodes.
As positive active materials of lithium secondary batteries, oxides, e.g., lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or lithium nickel cobalt manganese oxide (e.g., Li[NiCoMn]O2 or Li[Ni1−x−yCoxMy]O2), which include lithium and a transition metal formed in a structure capable of intercalation of lithium ions, may be used.
Carbonaceous materials in various forms, such as artificial graphite, natural graphite, or hard carbon, which allow intercalation and deintercalation of lithium ions, and non-carbonaceous materials such as silicon (Si), have been studied for use as negative electrode active materials of lithium secondary batteries.
Such non-carbonaceous materials can provide a very high capacity density, e.g., ten times or greater than that of graphite. However, the volumetric expansion and contraction of non-carbonaceous materials and a continuous reaction between the non-carbonaceous materials and the electrolyte during charge and discharge of the lithium secondary batteries may deteriorate the capacity retention rate, charge/discharge efficiency, and battery life characteristics of a battery. Therefore, there remains a need for an improved negative active material with improved charge/discharge performance.